1. Field of the Invention
The invention relates to a method for monitoring whether the switching threshold of a switching transducer, especially of a comparator, lies within a predefined tolerance range or not.
2. Description of the Related Art
In numerous applications, switching processes take place as a function of measured values or signal quantities. For instance—to name just a few of numerous applications by way of an example—for purposes of the two-point regulation of a temperature, for monitoring the internal pressure in a pressure vessel, for limiting the current in a cable, for brightness-dependent switching street lamps on and off, for triggering smoke alarms and sprinkler systems in case of fire, for operating anti-collision proximity sensors, for operating an anti-blocking system or a brake wear display in a vehicle, or for automatically switching off an industrial robot when a person approaches, there can be a need to trigger a switching procedure when a measured value or other signal exceeds or falls below a predefined threshold value. The threshold value thus defines a switching threshold.
These examples already show that malfunctions with such switching procedures can not only disrupt an operational sequence but also endanger considerable material values and especially the safety of humans.
During such switching procedures, malfunctions can be caused especially in that the threshold value moves away from a target value without being noticed, i.e. drifts uncontrolled. Such a switching threshold drift can be the result of, for example, temperature fluctuations, ageing, dirt, wear and tear, or production flaws in components; in the case of systems controlled by computers or microprocessors, the possible causes can also include software errors and program crashes.